This invention relates to an automatic, keyboard-operated paper insertion and ejection mechanism for typewriters, calculators or similar office machines. While the invention is described and claimed in connection with a typewriter, the invention is equally applicable for use in calculators or similar office machines.
Modern office machines perform various machine functions by automatic, keyboard-controlled mechanisms which were previously performed by manually operated mechanisms. It has been found that many of the manually operated mechanisms cannot be adapted to keyboard-controlled operation, but must be replaced by specially suited automatic mechanisms. Two such functions are the paper insertion function and the paper ejection function.
To automatically feed the paper to printing position in response to a keyboard-mounted switch, the machine mechanism must lift the paper bail, which is normally biased into engagement with the platen, off the platen so that the paper may be readily inserted between the platen and the bail-mounted pressure rolls as the platen-entrained paper advances with the platen. To complete insertion of the paper, the paper bail must be restored to apply pressure to the platen-entrained paper. Similarly, in response to a keyboard switch-actuated signal, the mechanism must also lift the paper bail to eject and allow withdrawal of the paper from between the bail and platen when printing has been completed. This requires a precision connection between the paper feed and the lifting mechanism, which is most conveniently achieved by a geared connection with the platen. However, the lifting and restoring mechanism must be disengaged from the paper feed mechanism during the line-indexing operation.